Fluid actuated pull gun



April 23, 1957' c, FFm-q EI'AL FLUID ACTUATED. PULL-GUN 5 Shets-Sheet 1 Filed April 27,1954

6 V R N 4. m 6% 7 April 23, 1957 c, GRlFFlTH ETAL 2,789,539

FLUID ACTUATED PULL GUN Filed April 27, 1954 5 Sheets-Sheet 2 April 23, 195 R. c. GRIFFITH E L I FLUID ACTUATED PULL GUN 5 Speets-Sheet 3 Filed April 27 1954 April 23, 1957 R. c. GRIFFITH EI' L FLUID ACTUATED PULL GUN 5 Sheets-Sheet 4 Filed April 37, 1954 I R. c. GRIFFITH AL FLUID ACTUATED PULL cuu April 23, 1957 5 Sheets-Sheet 5 Filed April 27, 1954 FLUID ACTUATED PULL GUN Raymond C. Grifiith and George J. Van Hecke, Detroit, Mich, assignors to Huck Manufacturing Company, De-

troit, Micln, a corporation of Michigan Application April 27, 1354, Serial No. 439,092

(Filed under Rule 47 (a) and 35 U. S. C. 116) 3 Claims. (Cl. 121-3) This invention relates to driving devices and, more particularly, to an improved fluid actuated pull gun for driving lock bolts, blind rivets and the like.

An object of the invention is to overcome disadvantages in prior devices of the indicated character and to provide an improved pull gun which facilitates the efficient driving of lock bolts, blind rivets and the like with a minimum of time, labor and expense.

Another object of the invention is to provide an improved fiuid actuated pullv gun incorporating improved control means which facilitates the intermittent actuation of the driving components while the gun is connected to a continuously operating source of fluid pressure.

Another object of the invention is to reduce operator labor fatigue by providing an improved pull gun that is compact, relatively light in weight, and which may be operated in relatively close quarters.

Another object of the invention is to provide an improved pull gun that is rugged in construction, economical to manufacture and assemble, durable and reliable in operation.

Still another object of the invention is to provide an improved pull gun which may be readily adapted to accommodate lock bolts, blind rivets and the like of various sizes and types.

The above as well as other objects and advantages of the present invention will become apparent from the following description, the appended claims and the accompanying drawings wherein:

Figure 1 is an elevational view, with portions in section, of a pull gun constructed in accordance with the present invention and showing the same applied to a fastening device;

Fig. 2 is an enlarged transverse sectional view of the structure illustrated in Fig. 1, taken on the line 22- thereof;

Fig. 3 is an enlarged transverse sectional view of the structure illustrated in Fig. 1, taken on the line 33 thereof;

Fig. 4 is an enlarged sectional view of a portion of the structure illustrated in Fig. 1, taken on the line 4--4 thereof;

Fig. 5 is an enlarged elevational view, with portions in section and other portions broken away, of the pull gun illustrated in Fig. 1;

Fig. 6 is an enlarged sectional elevational view of a portion of the structure illustrated in Fig. 5;

Fig. 7 is an enlarged transverse sectional view of a portion of the structure illustrated in Fig. 5, taken on the line 7--7 thereof;

Fig. 8 is an enlarged longitudinal sectional view of the valve housing, taken on the line 88 of Fig. 7; and

Figs. 9 through 12 are longitudinal sectional views of a portion of the pull gun illustrated in Fig. 1 and showing the components thereof in successive operating positions.

Referring to the drawings, a preferred embodiment of the invention is shown incorporated in a hydraulic pull gun, generally designated 20, for driving lock bolts, blind n'te States Patent 2,789,539 Patented Apr. 23, 1957 rivets and the like, although it will be understood that the invention is applicable to other uses. A fastening device of a type that may be driven by the pull gun of the present invention is shown in Figs. 1 and 4. Such fastening devices include a pin 22 having a head portion 24 and a shank portion 25, provided with longitudinally spaced pull grooves 26. The pin 22 is adapted to be inserted through a workpiece 28 from the outer side thereof and a collar 30 is fitted over the pin 22 on the outer side of a workpiece 32 and thereafter clinched to the pin 22. The workpieces 28 and 32 may comprise a pair of plate members having aligned apertures 34 and 36 therein through which the shank portion 25 of the pin 22 extends, the head portion 24 of the pin being adapted to engage the surface 38 of the plate 28 while the collar 30 is adapted to engage the surface 40 of the workpiece 32. The fastening device is set by pulling the pin 22 and applying the reaction force to the collar 30. After the desired pulling force is obtained, the collar 30 is locked to the pin 22 and upset against the adjacent workpiece 32. Subsequently, the shank portion 25 of the pin 22 is broken under tension at a weak portion adjacent the collar 30. The details of the fastening device form no part of the present invention, the fastening device and workpieces being shown merely to typify an important use of the invention.

The pull gun of the present invention includes a head piece, generally designated 42, which defines a longitudinally extending bore 44. A piston 46 having an integral rod 47 is mounted for reciprocation in the bore 44 of the head piece 42, the piston 46 being provided with suitable sealing rings, such as 48 and 50, which form a fluid tight seal between the piston and the head piece 42.

A longitudinally extending passageway 52 is formed in the head piece 42 in radially spaced relationship to the bore 44. One end of the passageway 52 is connected to the rod end of the bore 44 by a radially inwardly extending port 54 while the distal end of the passageway is closed by a plug 56 threadably fitted in the passageway 52.

An elongate valve housing 58 is fitted in the bore 44 in the head piece 42 and secured to the head piece by a snap ring 60. The inner end portion 62 of the valve housing 58 is reduced in diameter and is adapted to fit in a recess 64 formed in the head end of the piston 46, sufiicient clearance being provided between the piston 46 and the reduced portion 62 of the valve housing 58 to permit the entrance of hydraulic fluid therebetween when the peripheral portion of the piston is adjacent the peripheral portion of the inner end of the valve housing. An axially extending bore 66, open at each end, is formed in the valve housing 58 and is adapted to slidably accommodate a distributor valve 68 and a bypass v lve 70 which will be described hereinafter in greater detail.

A longitudinally extending inlet passageway 72 is pro longitudinally extending outlet passageway '74 is provided in' the valve housing 58 diametrically opposite the inlet passageway 72 and in radially outwardly spaced relationship with respect to the bore 66, the longitudinal axes of the inlet passageway 72 and the outlet passageway 74 extending in a direction substantially parallel to the longitudinal axis of the bore 66. A plurality of longitudinally spaced annular grooves 76, 78, 80, 82, 84, 86 and 88 are formed in the inner wall of the valve housing 58. The inlet passageway 72 is connected to the grooves and 86 by radially outwardly extending ports 90 and 92, while the outlet passageway 74 is connected to the grooves- 76, 84 and 88 by radially outwardly extending ports 94, 96 and 98.

An annular groove 100 is formed in the outer wall of; the. valve housing 58,, the groove 100 being substantially concentric with the groove 78. The groove 100 is connected to the passageway 52 by a port 104 and is also connected to the groove 78 by a radially outwardly extending port 106, the port 106 being circumferentially spaced from the outlet passageway 74.

For the purpose of forming a fluid tight seal between the valve housing 58 and the head piece 42, sealing members 108 and 110, preferably formed of a material which is not affected by the fluid utilized in the pull gun, are fitted in grooves 112 and 113, respectively, formed in the outer wall of the valve housing on opposite sides of the groove 100.

As best seen in Figs. 7 and 8, valve housing 58 also defines a longitudinally extending duct 114 which is disposed in radially spaced relationship with respect to the axially extending passageway 66. The end of the duct 114 adjacent the piston 46 i open and the distal end of the duct 114 is connected to a cross port 115 which communicates with the groove 82 in the valve housing.

As previously mentioned, the distributor valve 68 is mounted for reciprocation in the bore 66 of the valve housing 58. A plurality of longitudinally spaced annular grooves 116, 118 and 120 are formed in the outer wall of the distributor valve 68, the grooves 116 and 118 being separated by a land portion 122 and the grooves 118 and 120 being separated by a land portion 124. The end portions of the distributor valve and the land portions 122 and 124 are of substantially the same diameter as the bore 66 and have a sliding fit in the bore 66 with the result that a substantially fluid-tight seal is formed between such peripheral portions of the distributor valve and the walls of the bore 66.

The distributor valve 68 defines an axially disposed longitudinally extending passageway 126 which is open at each end and is adapted to accommodate a tubular actuating rod 128 which is slidably mounted in the passageway 126 and extends through the distributor valve. An actuating head 130 having a shank portion 132 and an enlarged head portion 134 is fixed to one end of the tubular actuating rod 128 and projects longitudinally outwardly therefrom. The shank portion 132 of the actuating head 130 is threadably fitted in an internally threaded passageway 136 provided in the piston 46 so as to secure the actuating head 130 to the piston. The tubular actuating rod 128 extends through the distributor valve 68 and the opposite end portion of the actuating rod is provided with a head 138 retained by a retaining ring 140.

The outer end portions of the bore 126 of the distributor valve are enlarged, as at 144 and 146, and a pair of coil springs 148 and 150 are fitted around the opposite end portions of the tubular actuating rod 128. One end portion of the coil spring 148 bears against the actuating head 130 while the opposite end of the spring 148 bears against an internal shoulder 152 provided on the distributor valve 68. One end portion of the coil spring 150 bears against an internal shoulder 154 while the opposite end portion of the coil spring 150 bears against the head 138.

The actuating heads 130 and 138 are of greater diameter than the enlarged portions 144 and 146 of the bore 126 of the distributor valve 68 and are adapted to bear against the ends of the distributor valve to shift the distributor valve during operation of the pull gun, as will be described hereinafter in greater detail.

For the purpose of releasably holding the distributor valve 68 in selected positions, a pair of spring biased detents 158 and 160 are mounted in radially extending openings 162 and 164 provided in the valve housing 58 on opposite sides of the distributor valve 68. The detents 158 and 160 are adapted to releasably engage longitudinally spaced notches 166 and 168 provided in the distributor valve 68 to releasably hold the distributor valve in selected positions, as will be described hereinafter in greater detail.

The bypass valve 70 is mounted for reciprocation in the bore 66 of the valve housing 58 in coaxial alignment with the distributor valve 68. The bypass valve 70 defines a longitudinally extending recess 170 adapted to accommodate the head 138 fixed to the actuating rod 128. An annular groove 172 is formed in the outer wall of the bypass valve 70 and the portions of the bypass valve 70 adjacent the groove 172 have a sliding fit in the bore 66 of the valve housing 58 so that the portions of the bypass valve 70 adjacent the groove 172 form substantially fluidtight seals between the bypass valve 70 and the valve housing 58.

In order to limit the longitudinal movement of the bypass valve 70, a radially extending flange 174 is provided on one end thereof, the flange 174 being adapted to engage an internal shoulder 176 provided on the valve housing 58. For the purpose of holding the bypass valve 70 in a selected position during reciprocating movement of the distributor valve 68, a push pin 178 is provided which extends through the tubular actuating rod 128 and the head 138, one end portion of the push pin 178 bearing against the surface 180 of the bypass valve while the opposite end of the push pin bears against a coil spring 182 fitted in the bore of the tubular actuating rod 128. The distal end of the coil spring 182 bears against the actuating rod 130.

A substantially cylindrical core piece 184 having an integral radially extending flange portion 186 on one end thereof is secured to the valve housing 58 by bolts 188 which extend through the flange portion 186 and threadably engage a flange portion 190 provided on the valve housing 58. A suitable gasket 192 may be inserted between the valve housing 58 and the core piece 184 to prevent the leakage of fluid. The core piece 184 defines a longitudinally extending inlet passageway 194 and a longitudinally extending outlet passageway 196. One end of the inlet passageway 194 is aligned coaxially with the inlet passageway 72 in the valve housing 58 while the opposite end of the inlet passageway 194 is connected to a supply hose 198, as at 200. One end of the outlet passageway 196 i coaxially aligned with the outlet passageway 74 in the valve housing 58 while the opposite end of the outlet passageway 196 is connected to an outlet hose 202, as at 204.

A front cam member 206 having cam surfaces 208 on one end thereof is slidably mounted on the core piece 184 intermediate the ends thereof, the front cam member 206 having a pair of radially outwardly projecting tenons 210 and 212 adapted to slidably engage longitudinally extending grooves 214 formed in a casing 216 which spacedly surrounds the core piece 184. One end of the casing 216 is rotatably mounted on the flange 186 of the core piece 184, while the opposite end of the casing 216 is provided with a radially inwardly extending flange 218 which is rotatably mounted on the outer end portion of the core piece 184. A transversely extending pin 220 is fixed to the front cam member 206 and extends transversely thereof through an elongate slot 222 provided in the core piece 184. The pin 220 is adapted to bear against one end of a throttle pin 224 slidably mounted in an axially disposed longitudinally extending passageway 226 defined by the core piece 184. The pin 224 extends through suitable sealing members 228 and 230 retained by a snap ring 232 and the distal end of the pin 224 bears against the end of the bypass valve 70. When the front cam member 206 moves longitudinally of the core piece 184 toward the valve housing 58, the pin 220 engages the pin 224 which, in turn, slides longitudinally of the passageway 226 so as to push the bypass valve 70 to the position illustrated in Figs. 5 and 6. For the purpose of moving the front cam member 206 longitudinally with respect to the core piece 184, a rear cam member 234 is provided having carn surfaces 236 thereon adapted to engage'the cam surfaces 208 of the front cam member 206. An annular slot 238 is provided in the casing 216 intermediate the end thereof and is adapted to receive an actuating ring 240 amnesia having a radially inwardly projecting tang 242 which ex? tends through the casing 216and engages an opening 244 in the rear cam member 234. With such a construc tion, rotation of the casing 216 relative to the core piece 184 causes the rear cam member 234 to rotate on the core piece 184 so that the cam surfaces 236 bear against the cam surfaces 208 in the front cam member 206 and cause the front cam member 206 to slide longitudinally of the core piece toward the valve housing 58. For the purpose of maintaining the cam surfaces 236 and 208 in operative relationship, a coil spring 246 is provided, the coil spring being interposed between the tenons 210, 212 on the front cam member 206 and the flange 186 on the core piece 184 so that one end of the coil spring 246 bears against the flange 186 while the opposite end bears against the tenons 210 and 212. A retaining pin 248 having a.

flat side 250 thereon extends through a transverse opening 252 provided in the core piece 184 and bears against the rear cam member 234 to hold the rear cam member in operative relationship with respect to the core piece 184.

A spring biased detent 254 is mounted in the core piece 184 and is adapted to selectively engage a plurality of circumferentially spaced slots 256 provided in the casing 216. Such a construction facilitates the positioning of the bypass valve 70 and also serves to hold the front and rear cam members 206 and 234 in selected positions so that the bypass valve 70 will be maintained in the desired position.

For the purpose of actuating a collet assembly, generally designated 262, which functions to pull the pin 22 of the fastening device through the aligned apertures 34 and 36 in the workpieces 28 and 32 and also functions to upset the collar 30 on the pin 22, a rocker arm 264 is provided. The rocker arm 264 is oscillatably mounted on a bearing 266 carried by depending flange portions 268 provided on the front end portion of the head piece 42. The rocker arm 264 includes a pair of angularly spaced bifurcated arms 270 and 272. The piston rod 47 is reduced in thickness, as at 274, at a position spaced from the end 276 hereof and the arm 270 of the rocker arm 264 is positioned over the reduced portion 274 of the piston 'rod 47 so that the outer end portion of the arm 270 bears against the shoulders 278 and 280 defining the reduced portion 274 of the piston rod.

The collet assembly 262 is comprised of an elongate tubular collet 282 defining a longitudinally extending bore 283, and the collet 282 is mounted in a passageway 284 defined by the head piece 42. An elongate anvil holder 286 is slidably mounted on the collet 282, the anvil holder 286 having a pair of longitudinally spaced flanges 288 and 290 projecting radially outwardly therefrom. The bifurcated arm 272 of the rocker arm 264 is fitted over the anvil holder 286 between the flanges 288 and 290, the outer end surfaces of the arm 272 bearing against the surfaces 292 and 294 of the flanges 288 and 290, respectively. With such a construction, oscillation of the rocker arm 264 causes the anvil holder 286 to slide longitudinally of the collet 282. The lower end portion 296 of the collet 282, as viewed in Fig. 4, is reduced in diameter and a swaging anvil 300 is interposed between the reduced diameter portion of the collet and the anvil holder 286, the swaging anvil 300 having a sliding fit on the reduced diameter portion 296 of the collet. The bore of the swaging anvil 300 is tapered adjacent the lower end thereof and is adapted to bear against the collar 30 of afastener to upset the collar against a workpiecewhen the hydraulic pull gun of the present invention is applied thereto. At a position adjacent the reduced portion 296 of the collet 282, a chuck 302 is positioned in the bore 283 of the collet, the chuck having three jaws 304 which are shaped generally in the form of a truncated cone. The bore 283 of the collet 282 is tapered at a position near but spaced from the lower end of the collet and the outer surfaces of the jaws 304 are adapted to bear against the wall 306 of the tapered portion of the bore 283 of the collet. The jaws 304 of the chuck are held in the operative relationship by a resilient retaining ring 308":

projecting flange 314 on one end thereof is fitted in the bore 283' of the collet 282, the flange portion 314 of the follower cap 312 bearing against the upper surfaces of the chuck jaws 304, as viewed in Fig. 4. An elongate follower member 316 having radially outwardly projecting flange portions 318 and 320 on the ends thereof is slidably mounted on a follower sleeve 322 fitted in the bore 283 of the collet 282. The flange portions 318 of the follower member 316 bears against a bumper 324 which is interposed between the follower member 316 and the follower cap 312 while the flange portion 320 of the follower member 316 bears against a washer 326 slidably mounted on the follower sleeve 322 and the washer 326, in turn, bears against one end of a column of O-ringS 328 fitted over the follower sleeve 322. The distal end of the column of O-rings 328 bears against a radially outwardly projecting flange 330 provided on the upper end of the follower sleeve 322, as viewed in Fig. 4. One end of a tubular spacer 332 bears against the flange 330 of the follower sleeve 322 while the opposite end of the spacer 332 bears against the inner end of a screw housing 334. fitted in the bore 283 of the collet 282 at a position adjacent the upper end thereof. The screw housing is provided with internal threads 336 adapted to threadably engage an externally threaded tubular adjustment screw 338, the inner end of which bears against a resilient, ringshaped bumper 340 which is interposed between the adjustment screw 338 and a radially inwardly projecting flange 342. provided on the screw housing 334. A cushion plate 344 is fitted over the adjustment screw 338 and the peripheral portion of the cushion plate bears against a resilient cushion 346 interposed between the cushion plate 344 and a radially outwardly projecting flange 348 formed integrally with the screw housing 334, the flange 348, in"

turn, bearing against the upper end of the collet 282. Such a construction serves to absorb the shock-imparted to a snap ring 350 which is fitted over the screw 338, the peripheral portion of the snap ring 350 being adapted to fit in a groove 352 in the head piece 42 to hold the collet assembly in the passageway 284 of the head piece 42.

In the operation of the pull gun, the rotation of the sleeve 216 in a clockwise direction, as viewed in Fig. 2, controls the actuation of the bypass valve 70 to the on or off position, the position of the bypass valve 70 being controlled by the front and rear cam members 206 and 234 which actuate the pin 224. In Figs. 5 and 6, the sleeve 216 is shown as being rotated so that the cam surfaces 236 of the rear cam member 234 engage the cam surfaces 208 of the front cam member 206 to move the front cam member 206 longitudinally of the core piece 184 toward the valve housing 58, the transversely extending pin 220 fixed to the front cam member 206, in turn, moving the pin 224 and the bypass valve 70 forwardly. The inner end of the bypass valve bears against the adjacent end of the distributor valve 68 and pushes the distributor valve 68 forwardly to the off or bypass position as shown in Figs. 5 and 6. Hydraulic fluid under pressure enters the. inlet passageway 194 defined by the core piece 184 from the supply hose 193 which is connected to a suitable source or reservoir of hydraulic fluid under pressure. The hydraulic fluid flows through the inlet passageway 194 and the inlet passageway 72 defined by the valve housing 58 to the ports and 92. A portion of the hydraulic fluid flows through the port 90, the groove 80, the groove 118, and the groove 78, through the cross port 106, the annular groove 100, and the port 104 to the passageway 52. The fluid then flows through the passageway 52, the cross port 54 to the rod end of the valve 68. At the same time, a portion of the hydraulic fiuidalso flows through the port 92, the annular groove 86, the groove-172, the groove 88 and the port 98, the.

outlet passageway 74 and through the outlet passageway 196 defined by the core piece to the Outlet hose 202 and back to the fluid reservoir. The oil at the head end of the piston is exhausted to the reservoir through the longi tudinally extending duct 114, to cross port 115, around the annular groove 82, the groove 120, the groove 84, and the port 96 to the outlet passageway 74.

Assuming that it is desired to impart reciprocatory motion to the piston, the casing 216 is rotated in a clockwise direction about the core piece 184, as viewed in Fig. 2 so that the actuating ring 240 rotates the rear cam member 234. The cam spring 246 then forces the front cam member 206 longitudinally of the core piece 184 toward the rear cam member 234 and at the same time, the distributor valve 68 is moved longitudinally of the valve housing 58 in a direction toward the core piece 184 by the energized front shift spring 148. As the distributor valve 68 moves, it forces the bypass valve 70 longitudinally of the valve housing 58 to the position illustrated in Fig. 9. When the components of the hydraulic gun are positioned in the manner illustrated in Fig. 9, the distributor valve 68 directs the hydraulic fluid from the inlet passageway 72 through the port 90, the groove 80, the groove 118, and the groove 82, through the cross port 115, the longitudinally extending passageway 114 to the head end of the piston 46, thereby driving the piston toward the rocker arm 264. The hydraulic fluid in the rod end of the bore 44 is exhausted to the reservoir through the port 54 and the passageway 52, the cross port 104, the groove 100, the port 106, the annular grooves 78, 116, and 76, and the port 94 to the outlet passageway 74. As shown in Fig. 10, the piston 46 thenmoves to the forward end of the bore 44 in the head piece 42. As the piston 46 moves forwardly, the distributor valve 68 is held in place by the spring loaded detent pins 158 and 160 which engage the notches 166 in the distributor valve. As previously mentioned, the actuating rod 128 is fixed to the piston bythe head 130 and the actuating rod 128 moves forwardly as the piston 46 moves forwardly. As the forward motion continues, the distributor valve rear shift spring 150 is compressed by the head 138 thereby increasmg the load on the spring 150 while the distributor valve front shift spring 148 is opened thereby decreasing the load on the spring 148. As the piston 46 approaches the end of its stroke, the actuating rod head 138 engages the distributor valve 68 and moves the distributor valve so that the detent pins 158 and 160 are disengaged from the notches 166. When the detent pins 158 and 160 are free of the notches 166, the energized rear shift Spring 150 shifts the distributor valve 68 to a position where the detent pins 158 and 160 snap into the notches 168 on the distributor valve 66, as shown in Fig. 11. At the same time, the push pin 178 bears against the bypass valve 70 to prevent the bypass valve 70 from moving forwardly as the distributor valve 68 shifts.

As the piston 46 moves toward the rocker arm, the shoulders 280 of the piston rod 47 bear against the arm 270 of the rocker arm 264 to rotate the rocker arm 264 in a counterclockwise direction about the longitudinal axis of the bearing 266, as viewed in Figs. 9 and 10. The arm 272 of the rocker arm 264 then bears against the flanges 298 of the anvil holder 286 and forces the anvil holder 286 to move longitudinally downwardly relative to the collet 282 so that the swaging anvil 300 bears against the collar 30 and moves the collar longitudinally relative to the shank 25 of the pin 22. At the same time, the tapered surfaces 306 of the collet 282 bear against the tapered surfaces of the chuck jaws 304 to hold the chuck jaws 384 in the closed position with the result that the chuck jaws grip the shank 25 of the pin 22 and pull the pin 22 through the apertures 34 and 36 of the'plates 28 and 32.

In Fig. 11 the piston 46 is shown at the forward and of its stroke. In this position, the distributor valve 68 has been shifted forwardly by the rear shift spring 150 so that the spring biased detents 158 and 160 engage the notches 168 in the distributor valve 68. In this position, the distributor valve 68 distributes hydraulic fluid from the inlet passageway 72 through the port 90, the groove 80, the groove 118 and the groove 78, through "the cross port 106, the groove 100, the port 104, and the passageway 52, the port 54 to the rod end of the bore 44 to drive the piston 46 rearwardly. Since the bypass valve 70 is maintained in the rear position, the hydraulic fluid is prevented from flowing through the port 92 and out of the groove 86 by the bypass valve. As the hydraulic fluid enters the rod end of the bore 44, the piston 46 starts its return stroke. As the piston 46 moves longitudinally of the bore 44 toward the distributor valve 68, the front shift spring 148 is compressed by the actuating rod head portion 134 thereby increasing the load on the spring 148 while the rear shift spring 150 is opened and the load thereon is decreased. As the piston 46 continues its rearward motion, the oil in the head end of the bore 44 is forced back to the reservoir through the longitudinally extending passageway 114, the cross port 115, the annular groove 82, the groove 120, the groove 84 and the port 96 to the outlet passageway 74, the fluid flowing from the outlet passageway 74 through the out let passageway 196 and the outlet hose 202 to the fluid reservoir as previously described.

With the casing 216 maintained in the on position by the detent 254 and the distributor valve 68 in the forward position, as shown in Fig. 11, the hydraulic fluid is directed from the inlet passageway 72 through the port 80, the groove 80, the groove 118, and the groove '78, through the cross port 106, the groove 100, the port 104, the passageway 52 and the port 54 to the rod end of the bore 44, thus forcing the piston 46 longitudinally of the bore 44 toward the position shown in Fig. 12. As the return stroke of the piston continues, the front shift spring 148 is compressed and the load thereon is increased. As the piston continues to move, the actuating rod head portion 134 engages the adjacent end of the distributor valve 68 and pushes the distributor valve so that the spring loaded detent pins 158 and 160 are disengaged from the notches 168. The shift spring 148 then shifts the distributor valve 68 longitudinally of the bore 66 of the valve housing 58 so that the detent springs 158 and 160 engage the notches 166 in the distributor valve 68. As the piston 46 moves back, it forces the hydraulic fluid in the head portion of the bore 44 back to the reservoir through the passageway 114, the cross port 115, the groove 82, the groove 120, the groove 84 and the port 96 to the outlet passageway 74. The fluid then flows from the outletpassageway 74 through the -outlet passageway 196 and the outlet hose 202 to the reservoir. 1

As the piston 46 moves toward the distributor valve 68, the shoulders 278 of the piston rod 47 bear against the arm 270 of the rocker arm 264 to rotate the rocker arm 264 in a clockwise direction about the longitudinal axis of the bearing 266, as viewed in Figs. 11 and 12. As the rocker arm 264 rotates, the arm 272 bears against the flanges 288 of the anvil holder 286 to move the anvil holder 286 upwardly relative to the collet 282.

At the same time, the chuck jaws 304, follower cap 312 and the chuck jaw follower 316 move upwardly relative to the follower sleeve 322 so that the flange 320 of the chuck follower 316 bears against the washer 326 and the washer 326, in turn, compresses the column of O- rings 328. The chuck jaws 304 also move upwardly When the piston 46 reverses its direction of travel, the chuck jaws 304 grip the shank 25 of the pin 22 at a position nearer the plate 32 and pull the pin 22 through the apertures 34 and 36, as previously described. When the piston 46 completes its rearward stroke, a full cycle is completed and the piston 46 is then positioned in the bore 44 of the head piece 42, as shown in Fig. 9, and ready to start its forward stroke. As the piston reciprocates, the chuck jaws 304 successively grip the shank 25 of the pin 22 at longitudinally spaced positions and pull the pin 22 through the apertures 34 and 36 in the plates 28 and 32. At the same time, the swaging anvil 300 engages the collar 30 of the rivet to force the collar 30 against the surface 40 of the adjacent plate 32. When the desired pulling force is obtained, the collar 30 is upset against the plate 32 and the shank 25 of the pin 22 is broken under tension at a weak portion adjacent the collar 30. The broken portion of the pin 22 then moves through the chuck jaws 304, the follower cap 312, the follower sleeve 322 and the tubular spacer 332 and is discharged through the bore of the tubular adjustment screw 338.

While a preferred embodiment of the invention has been shown and described, it will be understood that various changes and modifications may be made without departing from the spirit of the invention.

What is claimed is:

1. A fluid actuated pull gun for driving blind rivets and the like, comprising a body defining an elongate bore, a piston reciprocally mounted in said bore, a valve housing fixed to said body and having fluid inlet and outlet passageways therein, means including a first valve for successively establishing fluid circuits from said inlet passageway to said bore on opposite ends of said piston to drive said piston in opposite directions, spring means actuable in response to the movement of said piston to shift said first valve between selected positions, and means including a second valve actuable to disable said spring means and to establish fluid circuits permitting a portion of the fluid flowing through said inlet passageway to flow to said bore on one end of said piston to hold said piston in a selected position and permitting the remaining portion of said fluid to bypass said bore in flowing from said inlet passageway to said outlet passageway.

2. In a fluid actuated pull gun, the combination including a body defining an elongate bore, a piston reciprocally mounted in said bore, a valve housing fixed to said body, said valve housing having a centrally disposed passageway therethrough and fluid inlet and outlet ducts spaced from said passageway, said passageway having a plurality of longitudinally spaced annular grooves in the wall thereof, means including a distributor valve mounted in said passageway and having a plurality of longitudinally spaced annular grooves therein registerable selectively with grooves in the walls of said passageway to successively establish fluid circuits from said inlet passageway to said bore on opposite ends of said piston to drive said piston in opposite directions, and means including a bypass valve mounted in said passageway and having an annular groove therein registerable with selected grooves in the wall of said passageway, said bypass valve being actuable to establish fluid circuits permitting a portion of the fluid flowing through said inlet passageway to flow to said bore to hold said piston in a selected position and permitting the remaining portion of said fluid to bypass said bore in flowing from said inlet passageway to said outlet passageway.

3. In a fluid actuated pull gun, the combination including a body defining an elongate bore, a piston reciprocally mounted in said bore, a valve housing fixed to said body, said valve housing having a centrally disposed longitudinally extending passageway therethrough and fluid inlet and outlet ducts outwardly spaced from said passageway, said passageway having a plurality of longitudinally spaced annular grooves in the wall thereof, means including a distributor valve mounted in said passageway and having a plurality of longitudinally spaced annular grooves therein registerable selectively with grooves in the walls of said passageway to successively establish fluid circuits from said inlet passageway to said bore on opposite ends of said piston to drive said piston successively in opposite directions, and means including a bypass valve mounted in said passageway and having an annular groove therein registerable with selected grooves in the Wall of said passageway and actuable to establish fluid circuits permitting a portion of the fluid flowing through said inlet passageway to flow to said bore on one end of said piston to hold said piston in a selected position and permitting the remaining portion of said fluid to bypass said bore in flowing from said inlet passageway to said outlet passageway.

References Cited in the file of this patent UNITED STATES PATENTS 1,597,413 Lee Aug. 24, 1926 1,931,452 Wheeler Oct. 17, 1933 1,965,038 Hartman July 3, 1934 2,355,520 Fischer Aug. 8, 1944 2,383,082 Rossmann Aug. 21, 1945 2,404,747 Sacchini July 23, 1946 2,443,568 Palm June 15, 1948 2,450,564 Sacchini Oct. 5, 1948 2,627,248 Shaft Feb. 3, 1953 FOREIGN PATENTS 63,691 Sweden Sept. 13, 1927 

